As far as I know all you can do is to Pause and Resume the music that its playing.
If you do something like this:
It will pause the current musing being played.
If you do this:
It will resume the music that was playing. You still need to check if something is playing and save a state to issue the resume instruction only if there is anything to be resumed.
Also take in consideration that if I recall correctly you need to ask user permission before pausing the music, as per rules of submission to the store. If in testing they see that you pause a music that its playing without asking authorization to do so, your app may fail the certification process.
Hope that helps you.